title: The pallidopyramidal syndromes: nosology, aetiology and pathogenesis.
abstract: OBJECTIVE
  The aims of this review is to suggest a new nomenclature and classification system for the diseases currently categorized as neurodegeneration with brain iron accumulation (NBIA) or dystonia-parkinsonism, and to discuss the mechanisms implicated in the pathogenesis of these diseases.
  
  
  RESULTS
  NBIA is a disease category encompassing syndromes with iron accumulation and prominent dystonia-parkinsonism. However, as there are many diseases with similar clinical presentations but without iron accumulation and/or known genetic cause, the current classification system and nomenclature remain confusing. The pathogenetic mechanisms of these diseases and the causes of gross iron accumulation and significant burden of neuroaxonal spheroids are also elusive. Recent genetic and functional studies have identified surprising links between NBIA, Parkinson's disease and lysosomal storage disorders (LSD) with the common theme being a combined lysosomal-mitochondrial dysfunction. We hypothesize that mitochondria and lysosomes form a functional continuum with a predominance of mitochondrial and lysosomal pathways in NBIA and LSD, respectively, and with Parkinson's disease representing an intermediate form of disease.
  
  
  CONCLUSIONS
  During the past 18 months, important advances have been made towards understanding the genetic and pathological underpinnings of the pallidopyramidal syndromes with important implications for clinical practice and future treatment developments.
authors.affiliation: Department of Molecular Neuroscience, Reta Lila Weston Research Laboratories, UCL Institute of Neurology, London, UK.
authors.forename: Eleanna
authors.initials: E
authors.lastname: Kara
authors.forename: John
authors.initials: J
authors.lastname: Hardy
authors.forename: Henry
authors.initials: H
authors.lastname: Houlden
mesh_terms: D001764:Blepharospasm / Q000145:classification* / Q000209:etiology* / Q000378:metabolism / Q000473:pathology*; D001921:Brain / Q000378:metabolism / Q000473:pathology; D002965:Classification; D005917:Globus Pallidus / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007501:Iron / Q000378:metabolism; D010302:Parkinson Disease, Secondary / Q000145:classification* / Q000209:etiology* / Q000378:metabolism / Q000473:pathology*
chemical_list: D007501:Iron